非同步式计数器的运作

1Chapter9Counters計數器1.AsynchronousCounterOperation非同步式計數器的運作2.SynchronousCounterOperation同步式計數器的運作3.Up/DownSynchronousCounters上/下數的同步式計數器4.DesignofSynchronousCounters同步式計數器的設計5.CascadedCounters串接計數器6.CounterDecoding計數器的解碼7.CounterApplications計數器的應用8.Troubleshooting檢修9.LogicalSymbolswithDependencyNotation具有相依註標的邏輯符號10.ProgrammableLogic可程式邏輯DigitalSystemApplication數位系統的應用2Figure8--40TheJ-Kflip-flopasadivide-by-2device.Qisone-halfthefrequencyofCLK.ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.Flip-FlopApplications正反器的用途除法器JKClkQQ00Q0Q0不變0101Reset1010Set11Q0Q0轉態3Figure9--1A2-bitasynchronousbinarycounter.ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.1.非同步式計數器的運作Figure9--2TimingdiagramforthecounterofFigure9-1.Asinpreviouschapters,outputwaveformsareshowningreen.100111004Figure9--3Three-bitasynchronousbinarycounteranditstimingdiagramforonecycle.ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.1.非同步式計數器的運作5Figure9--4Propagationdelaysina3-bitasynchronous(ripple-clocked)binarycounter.ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.1.非同步式計數器的運作6Figure9--5Four-bitasynchronousbinarycounteranditstimingdiagram.ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.1.非同步式計數器的運作例題9-1如圖9-5所示為一個4位元的非同步二進制計數器,每一個正反器都是負緣觸發而且有一個10ns的極際延遲時間.(1)設計各正反器輸出的時序圖,(2)算出從Clock輸入加訊號進去到Q3輸出的延遲時間,(3)算出最高工作頻率.Sol:(2)tp(Total)=4x10ns=40ns(3)fmax=1/tp(Total)=1/40ns=25MHz7ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.1.非同步式計數器的運作Figure9--6Anasynchronouslyclockeddecadecounterwithasynchronousrecycling.8ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.例題9-2證明一個非同步的計數器如何除12,從二進制的0000算到1011.1.非同步式計數器的運作Figure9--7Asynchronouslyclockedmodulus-12counterwithasynchronousrecycling.很尖銳的脈波9FigureA--21The74LS93A4-bitasynchronousbinarycounterlogicdiagram.(Pinnumbersareinparentheses,andallJandKinputsareinternallyconnectedHIGH.)ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.1.非同步式計數器的運作10FigureA--22Twoconfigurationsofthe74LS93Aasynchronouscounter.(Thequalifyinglabel,CTRDIVn,indicatesacounterwithnstates.)ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.1.非同步式計數器的運作11FigureA-2374LS93Aconnectedasamodulus-12counter.ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.1.非同步式計數器的運作例題9-3證明74LS93A如何作為一個除12的計數器.12A2-bitsynchronousbinarycounter.ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.2.同步式計數器的運作Figure9--10TimingdiagramforthecounterofFigure9-11.13Figure9--9Timingdetailsforthe2-bitsynchronouscounteroperation(thepropagationdelaysofbothflip-flopsareassumedtobeequal).ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.2.同步式計數器的運作第一個脈波第二個脈波第三個脈波第四個脈波解釋前一頁每次Clock來時Q0及Q1的變化14Figure9--11A3-bitsynchronousbinarycounter.ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.2.同步式計數器的運作Figure9--12TimingdiagramforthecounterofFigure9-14.15ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.2.同步式計數器的運作FF2在Q0Q1同時為1時,下一個脈波來會改變狀態,FF3則在Q0Q1Q2同時為1時,下一個脈波來才會改變狀態,Figure9--13A4-bitsynchronousbinarycounterandtimingdiagram.PointswheretheANDgateoutputsareHIGHareindicatedbytheshadedareas.16Figure9--14AsynchronousBCDdecadecounter..ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.2.同步式計數器的運作Figure9--15TimingdiagramfortheBCDdecadecounter(Q0istheLSB).17FigureA--24The74HC1634-bitsynchronousbinarycounter.(ThequalifyinglabelCTRDIV16indicatesacounterwithsixteenstates.)ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.2.同步式計數器的運作18FigureA--25Timingexamplefora74HC163.ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.2.同步式計數器的運作19FigureA--26The74LS160synchronousBCDdecadecounter.(ThequalifyinglabelCTRDIV10indicatesacounterwithtenstates.)ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsreserved.2.同步式計數器的運作20FigureA--27Timingexamplefora74LS160.ThomasL.FloydDigitalFundamentals,8eCopyright©2003byPearsonEducation,Inc.UpperSaddleRiver,NewJersey07458Allrightsr